1. Field of the Invention
This invention relates to mechanisms for quickly releasing a tow cable from the towing vessel thereof notwithstanding the magnitude of the tensile towing load carried by the tow cable which, in the normal case, tends to lock any towing mechanisms against any releasing movement. More particularly, the invention relates to towing mechanisms having a releasable and securable pelican hook means for retaining the end of a tow cable during towing, wherein during normal towing operation the tensile load in the tow cable passes through the axis of rotation of said pelican hook, and once the pelican hook is caused to move toward a released position the tensile load is caused to pass through a line other than above mentioned, thereby imparting an opening moment or bias to the pelican hook.
2. Description of the Prior Art
Of interest is U.S. Pat. No. 102,067 to Tuttle and Peterson which shows a releasable pelican hook tow cable securement device. The line of force carried by the tow cable of Tuttle, however, at no time passes through the axis of rotation of said hook, and as a result there is a constant opening or pivoting bias carried by the hook and its related structure which may lead to premature fatigue of the mechanism. Also of interest is U.S. Pat. No. 4,540,210 to Smith which shows a cable release mechanism of the remote control variety wherein a pelican hook is released by the linear sliding movement of a keeper ring. Smith also discloses a cable seat connected to a pivotable pelican hook wherein the line of action of the tow cable is deliberately held in a plane generally about the axis of rotation of the pelican hook, which causes there to be a constant moment about the axis of rotation of the pelican hook while the device of Smith is in use. Such a configuration can lead to premature wear and fatigue of the elements.
As in Tuttle, the tensile load carried by the tow cable of Smith does not pass through the axis of rotation of the pelican hook and consequently there is a constant opening bias exerted on the device that may lead to an unwanted and potentially dangerous result should the keeper ring fail and a towed barge be set free to drift.
Improvements to the earliest pelican hook cable securement mechanisms have primarily been directed toward providing release capability to mechanisms under a heavy tensile load carried by the tow cable. Normally the pelican hook had to be released by sharply striking it with a sledge hammer to release the keeper ring. Improvements thereto have included providing remote control (i.e.: hydraulic) means for releasing the pelican hook from engagement with the keeper ring. Such attempts have introduced complicated structure to the devices and the consequent difficulties associated therewith. Further, no devices have been heretofore presented which cause the towing load to be directed through the axis of rotation of the pelican hook whereby there is no dangerous tendency for the pelican hook to rotate away from its containment position during towing operation. When it is desired to release the cable from the cable release mechanism of the instant invention, one merely removes the retaining member from engagement with the end of the pelican hook which motion in and of itself simultaneously causes the tow force to be moved to a position passing above the axis of rotation of said pelican hook wherein the pelican hook is urged open by the moment thus created.